What is the largest particle size in soil classification?

The largest particle size in soil classification is gravel. Soil is classified based on particle size, and gravel consists of larger particles, typically greater than 2 mm in diameter. This makes it the coarsest material in the soil textural triangle, which categorizes soils into gravel, sand, silt, and clay based on their relative sizes.

Understanding the distinction in particle size is crucial because it affects soil properties such as drainage, water retention, and compaction. Gravel has high permeability, allowing water to flow through it relatively easily, which is an important consideration in on-site sewage facilities to prevent clogging and ensure effective drainage.

In contrast, sand, silt, and clay have smaller particle sizes, with sand falling between gravel and silt, and clay being the finest. Each of these types of soil plays a significant role in the overall function and effectiveness of septic systems but does not surpass gravel in particle size.